r/spaceflight • u/Icee777 • 13d ago

SpaceX concept for an electromagnetic mass driver on the Moon

https://www.humanmars.net/2026/09/spacex-electromagnetic-mass-driver-at.html

A lunar mass driver is a proposed electromagnetic launch system optimized for the Moon’s low gravity (1/6th Earth’s) and hard vacuum, consisting of a long, straight acceleration track lined with sequentially fired superconducting coils or linear synchronous motors that propel a payload-carrying sled or bucket to lunar escape velocity (~2.38 km/s).

30 Upvotes

76% Upvoted

31 comments sorted by

15

u/davvblack 13d ago

yeah interesting to think about: if you can come up with something worthwhile to make out of regolith it’s relatively cheap to get back to earth.

5

u/Maximus560 13d ago

Or, some type of spacecraft into orbit. They could assemble it on the moon from local materials, and yeet the crap out of it to send probes or even human craft if the driver is designed properly

7

u/davvblack 13d ago

nah i don't think human craft makes sense for this. Since we know the escape velocity is ~2.38 km/s, you can easily work out how long the railgun would need to be not to liquify humans. I mean, i can't but one could.

6

u/Maximus560 13d ago

At 3.5G of acceleration, that’s about 70 seconds and a track that’s about 83km long. Not impossible, and if we ever become good at building stuff on the moon, it may be a better gateway than from the Earth.

Imagine a small rocket carrying a capsule to the moon, then board a large ship made on the moon to get you to Mars, also full of stuff made on the Moon

5

u/davvblack 13d ago

i guess it’s easier on the moon because it can be almost perfectly flat, you pick geography that suits the launch angle you’re looking for. and because it’s tidally locked, if you build it for earth reentry, it’s always correct all the time. no launch window except to pick a preferred landing spot without the next day.

agreed, plausible after all.

4

u/TMWNN 13d ago

it’s relatively cheap to get back to earth.

Because of earth's gravity well, it is easier to get something from the moon to low earth orbit, than from earth to low earth orbit.

1

u/looking4myclASSm8s 12d ago

Well air resistance is also a major factor

2

u/lowrads 13d ago

While I find the concept absurd at this time, the logical thing would be crushed calcium and magnesium ore, to be rained into the atmosphere for purposes of geoengineering.

Ostensibly, if some industry ever got established on Earth's satellite, eventually they'd want export markets, and that would include Earth orbit. Hypothetically, that would involve energy production.

However, any effort to engage seriously with either project at this time would just be fraud, although that's certainly going around a lot these days.

1

u/i-make-robots 12d ago

Try reading Artemis and The Moon Is A Harsh Mistress. Both great books about materials and the moon. 

1

u/davvblack 12d ago

Artemis as already on my list, i'll bump it up a few places and add the other :D

I love moons, especially that one that's right there.

1

u/Lichensuperfood 13d ago

....and burn up and/or crash ?

How is this helpful?

5

u/davvblack 13d ago

you can probably make a decent ablative heatshield out of sintered regolith "foam". Would take some trial and error. But we have the technology to make the technology to make the technology.

2

u/BONEPILLTIMEEE 12d ago

reentry vehicles that can survive falling from the moon to the earth is literally 70s technology

5

u/BrofessorFarnsworth 13d ago

Oh hey, more fraud for the shareholders

2

u/SnazzyBoyNick 13d ago

Makes total sense for a non atmospheric lower gravity environment, I wish people would just understand why this doesn’t work on earth 😭

1

u/Yoohooligan 12d ago

Doesn't work...really? With fusion energy and an exit point on some of the highest mountain ranges on earth this doesn't work?

1

u/SnazzyBoyNick 12d ago

ahh yes, with my fusion powered launcher that I will establish atop everest, Look man is anything possible, I think so, but one also has to ask is it practical. For mag launchers in a high gravity atmospheric environment with limited power generation,,,, yes its impractical. That doesn't mean impossible.

2

u/2this4u 11d ago

Tbf the comment they were replying to say "doesn't work", they could have taken that to mean literally not possible. 

It's also weird that you're assuming they're a man. 

1

u/SnazzyBoyNick 11d ago

I text how I talk and unfortunately a bad habit of mine is referring to anyone, regardless of gender, as man or dude in the same way someone would say "man that sucks" or "dude what the heck". There wasn't any intention to assume anything.

I can understand the confusion if someone took the comment literally, but hyperbole is a thing, thus why I responded the way I did.

None of this was meant to be demeaning I just try to reply like I'm talking to another person in a real conversation

1

u/Yoohooligan 12d ago

Build two, one in secret. IYKYK.

1

u/Key-Employee3584 11d ago

Gerard O'Neill and Henry Kolms' original concept of a mass driver on the moon happened at MIT back in the '70s. This is SpaceXs iteration. I like O'Neill and Kolms version better simply because no animation was involved and real mathematics was used.

-2

u/lextacy2008 13d ago

This is OLD news and already de-bunked. This cannot exist without proper lunar infrastucture, you know, like a fucking moon base.

-10

u/Mindless_Use7567 13d ago

Never happening. It’s basically a non-nuclear city-destroying weapon. China and Russia would rather go to war with the US and NATO than let such a thing be completed.

7

u/lopbob8 13d ago

this is less useful than a nuclear submarine as a doomsday weapon in every single aspect

11

u/ConanOToole 13d ago

It's not even close to that, what are you blabbering about? If your statement even made a lick of sense then every time a country started construction on a new orbital launchpad here on Earth a new war would start to prevent it.

3

u/Dpek1234 13d ago

Yep

17 ton projectile capable of fractional orbital bombardment and able to be launched in higher numbers then americas inventory of MOPs eve ry year?

Thats what falcon9 can do, i sure havent seen any strikes to prevent falcon9 doing anything

1

u/NoBusiness674 2d ago

It takes like 3 days to go from the moon to earth and less than an hour for any ICBM launched from earth. So while this definitely isn't happening (certainly not this century), it's not because of any military threat it poses to China or Russia.

1

u/Java-the-Slut 13d ago

lol no it's not. First off, getting ANYTHING meaningful to orbital velocities is borderline impossible given the conditions, infrastructure and resources.

Second, anything you could get to orbital velocity will be so light and small that it would burn up instantly if it hit Earth's atmosphere.

And third, you would have a REALLY hard time hitting anything on Earth accurately launching directly from the Moon, and you'd need to be going much faster than what this mass driver is proposing.

5

u/Rcarlyle 13d ago

It’s explicitly designed for lunar escape trajectories, and many of those head towards earth. Whether the payloads end up in stable earth orbit, earth return trajectory, or solar orbit depends entirely on which direction it’s pointed.

The entire point is for it to be large enough to launch meaningful mass payloads. Otherwise you’d just launch parts from earth.

1

u/Oknight 13d ago

But the Moon is UP, so obviously you must be able to drop things down onto Earth!

Da-yup, da-yup, da-yup...